Techniques for detecting high impedance conditions in an electrical grid are described herein. In one example, impedance is calculated for each of a plurality of locations within the electrical grid, such as at electrical meters. The impedances may be calculated as a change in voltage divided by a change in current, such as between sequential voltage/current measurements. Statistics may be maintained, including the calculated impedances. In three examples, statistics may be used to identify growth in impedance over multiple days, to identify growth in impedance over multiple hours, and to identify a meter for which impedance is higher than impedance for other meters attached to a single transformer. In a further example, instances of impedance over a threshold value may be identified, from among the maintained statistics. The instances of high impedance may be reported for reasons including cost and safety.
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1. A method to determine a voltage of a secondary of a transformer, the method comprising: under control of one or more processors configured with executable instructions: receiving a plurality of voltage and current measurements of each of a plurality of meters associated with the transformer; determining a size of a group of meters, from among the plurality of meters, that measured voltage change magnitudes that are greater than explained by corresponding current change magnitudes; calculating impedance values of each of the plurality of meters associated with the transformer to obtain calculated impedance values, wherein the calculated impedance values are based at least in part on measurements made at each of the plurality of meters; utilizing the calculated impedance values for each of the plurality of meters, and at least some of the plurality of voltage and current measurements, to calculate, for each respective meter, a transformer secondary voltage value; averaging the calculated transformer secondary voltage value from each of the meters to calculate an averaged transformer secondary voltage value; recognizing instances of impedance over an impedance threshold from among the calculated impedance values; distinguishing from among the recognized instances, power diversion and infrastructure degradation, based at least in part on the size of the group of meters; and reporting the averaged transformer secondary voltage value and at least one of infrastructure degradation and power diversion.
2. The method of claim 1 , wherein the method additionally comprises: dividing a change in measured voltage by a change in measured current at each of the plurality of meters.
3. The method of claim 1 , wherein the method additionally comprises: accessing a time series of paired voltage and current measurements; and calculating an impedance value based on at least two pairs of measurements from within the time series.
4. The method of claim 1 , wherein the method additionally comprises: identifying growth in impedance in one or more of the plurality of meters over multiple calculated impedances associated with multiple days; identifying growth in impedance in one or more of the plurality of meters over multiple calculated impedances associated with a day or less; identifying a meter for which impedance is higher than impedance for other meters associated with the transformer; and identifying a meter having impedance greater than a threshold value.
5. The method of claim 1 , wherein the method additionally comprises: identifying meters that have impedance values over a first threshold value or instances of impedance change over a second threshold value; locating at least one upstream meter of one or more of the identified meters; and calculating an impedance of the at least one upstream meter.
6. The method of claim 1 , wherein the method additionally comprises: tracking data showing loads over time with respect to an individual meter; and determining if calculated impedance over a first threshold value or impedance change over a second threshold value indicate power provided through degraded infrastructure or power diversion within an electrical grid based at least in part on the data showing loads over time.
7. The method of claim 1 , wherein the method additionally comprises: comparing instances of the averaged transformer secondary voltage value of the transformer to a threshold of permitted voltage variability; and responsive to the comparing exceeding the threshold of permitted voltage variability, flagging the transformer for possible electrical diversion.
8. A system, comprising: a processor; memory in communication with the processor; data, based on voltage and current measurements, maintained in the memory; and an analytics application, operable by the processor and defined at least in part in the memory, to utilize the data and to perform actions comprising: calculating impedance values of a meter to obtain calculated impedance values, wherein the calculated impedance values are based at least in part on: voltage and current measurements made at a plurality of different times; and voltage and current measurements indicating a plurality of different load conditions; utilizing at least some of the calculated impedance values to calculate a secondary voltage value of a transformer to which the meter is connected; ranking a plurality of transformers based on calculated secondary voltage values; determining that no transformer load change was contemporaneous with a change in the ranking of the plurality of transformers; and responsive the determination, reporting possible theft.
9. The system of claim 8 , wherein the actions additionally comprise: comparing instances of the calculated secondary voltage value of the transformer taken over time to a threshold of permitted voltage variability; and responsive to the compared instances exceeding the threshold of permitted voltage variability, flagging the transformer for possible electrical diversion.
10. The system of claim 8 , wherein the actions additionally comprise: comparing the calculated secondary voltage value of the transformer to predicted voltage based at least in part on voltage falloff of transformers based on distance from a substation; and responsive to the calculated secondary voltage value being less that predicted voltage, flagging a possible existence of an unauthorized transformer or an unauthorized load.
11. The system of claim 8 , wherein the actions additionally comprise: comparing secondary voltages of transformers on a same feeder line; establishing the ranking of the plurality of transformers based at least in part on the comparing; detecting the change in the secondary voltage ranking; and reporting the detected change.
12. The system of claim 8 , wherein the actions additionally comprise: comparing secondary voltages of transformers on a same feeder line; and providing information about a location of an unauthorized transformer based at least in part on the comparison.
13. The system of claim 8 , wherein the actions additionally comprise: identify a voltage drop at the transformer that is not correlated to current use measured by meters connected to the transformer; and report a likelihood of power diversion located at the transformer.
14. The system of claim 8 , additionally comprising: one or more data concentrator devices, to process instances of secondary voltage values and/or instances of change between sequential updates of calculated transformer secondary voltage values.
15. One or more non-transitory computer-readable media storing computer-executable instructions that, when executed, cause one or more processors to perform acts comprising: receiving a plurality of measured voltage and current values from a plurality of metrology devices of a plurality of meters, respectively; calculating impedance values of each of the plurality of meters based on the plurality of measured voltage and current values to obtain calculated impedance values, wherein the calculated impedance values are based at least in part on measurements made at the plurality of meters; utilizing the calculated impedance values for each of the plurality of meters, and at least some of the plurality of measured voltage and current values, to calculate, for each respective meter, a transformer secondary voltage value of a transformer; averaging the calculated transformer secondary voltage values of the respective meters to calculate an averaged transformer secondary voltage value; identifying if a level of variability of the averaged transformer secondary voltage value, when calculated a plurality of times, exceeds a threshold of variability; and responsive to the level of variability for the transformer exceeding the threshold of variability, reporting the transformer.
16. One or more non-transitory computer-readable media as recited in claim 15 , additionally comprising: determining which of the plurality of meters are experiencing impedance over a threshold and which are not experiencing impedance over the threshold, providing information about a location of a circuit problem based at least in part on the determination.
17. One or more non-transitory computer-readable media as recited in claim 15 , wherein the acts additionally comprise: distinguishing meters having high impedance due to degraded infrastructure from meters having high impedance due to diversion of electricity, wherein the distinguishing is based at least in part on at least one of: a size of a group of meters for which a change in voltage is greater than an expected threshold value based on a magnitude of a change in current; and a comparison of commonly seen loads, over time, for particular meters.
18. One or more non-transitory computer-readable media as recited in claim 15 , wherein at least some of the acts are performed by operation of processors on: the plurality of meters; a back-office server; a circuit card in a meter; a concentrator; or a router.
19. One or more non-transitory computer-readable media as recited in claim 15 , wherein the acts are performed in part by operation of processors on each of the plurality of meters, and additionally comprise: receiving a time series of paired voltage and current measurements; and calculating impedance based on sequential pairs of voltage and current measurements.
20. One or more non-transitory computer-readable media as recited in claim 15 , wherein the acts are performed in part by operation of processors on each of the plurality of meters, and additionally comprise: identify a voltage drop at the transformer that is not correlated to current use measured by meters connected to the transformer; and report a likelihood of power diversion located at the transformer.
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July 1, 2019
July 28, 2020
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